Anheuser-Busch InBev sold 17.7 million barrels of Budweiser last year, less than the 18.2 million barrels of Coors Light, according to Beer Marketer's Insights. Bud Light retains the No. 1 spot.

Reporting from St. Louis — After years of gaining ground, the Silver Bullet has finally caught the King.

Coors Light outsold Budweiser last year to become the nation's second-most-popular brew after Bud Light, according to estimates by an industry trade publication.

Beer Marketer's Insights reported this week that Anheuser-Busch InBev sold 17.7 million barrels of its flagship lager in the U.S., less than the 18.2 million barrels that beer drinkers bought of Coors Light. It marks the first time in nearly two decades that Anheuser-Busch hasn't claimed the two top spots on sales charts.

It comes amid a broad downturn in beer sales, especially for the big boys such as Anheuser-Busch and MillerCoors. Beer Marketer's Insights estimates that Anheuser-Busch's volume fell 2.9% last year, and that sales of its beer hit the lowest point in a decade. MillerCoors' volume fell at roughly the same clip, though its biggest label, Coors Light, grew through aggressive marketing and broader distribution, said Eric Shepard, the newsletter's executive editor. Coors Light's gain was small, just 0.8%, but that was enough for it to finally top Budweiser.

Anheuser-Busch, which will release its official 2011 sales figures in March, had little comment on the report. A spokesman said the company is "committed to stabilizing Budweiser."

Bud's market share has been falling for years as drinkers have quit full-calorie domestic beers in favor of either light beers or higher-end craft brews. And MillerCoors has made no secret of its ambition to unseat Budweiser, which Anheuser-Busch calls the King of Beers.

"It was just a matter of time," Shepard said. "Unless A-B did something really radical to boost the brand, this was really just a question of when."

The sales decline of 4.6% was actually Budweiser's best performance in some years — volume fell 7% in 2010 and nearly 10% in 2009 — and the brand's results improved as 2011 wore on. Since it bought Anheuser-Busch in 2008, InBev has made growing Budweiser, both here and overseas, one of its priorities. And it still is.

Last year the company introduced new cans designed to enliven the brand's image, and it has launched new ad campaigns targeting twentysomethings, who are key to Bud's future.

Chief Executive Carlos Brito also sees a lot of potential for growth overseas, where the name Budweiser and all the Americana it connotes still carry a lot of weight, and a competitor such as Coors Light barely registers.

The company launched Budweiser in Russia in 2010 and Brazil last year. It says sales are up in places such as China and Britain. And it has secured sponsorship rights for the next three World Cups as part of its strategy to sell Bud in emerging markets. Those efforts are beginning to pay off; through the first nine months of 2011, global Budweiser sales grew 2.5%.

So even if it's now No. 3 at home, the King is climbing the charts overseas.

Still, Budweiser's long decline — in 1988 it sold 50 million barrels — means that there's a lot of people for whom the King of Beers is an afterthought, or at least something their dad drinks.

"There's a whole generation out there who never drank Bud," Shepard said. "My kids are in their 20s. They've never drank Bud."